Lead poisoning has been recognized as a major health problem in this country since at least the 1930s, but it continues to threaten many Americans, particularly children. The Centers for Disease Control and Prevention issued new guidelines last week estimating that roughly 535,000 youngsters may have unsafe levels of the toxic metal in their blood. Lead is found in drinking water and has many industrial uses. But the worst of the threat comes from lead-laden paint — now outlawed but often still found on the walls of old houses and apartments. Public health historians Gerald Markowitz and David Rosner fault paint makers and marketers, along with regulators, landlords and others, for letting the hazard persist.  They also point the finger at researchers. Their new book, “Lead Wars,” details how federally funded researchers in the 1990s with Baltimore’s Kennedy Krieger Institute studied children as they were developing lead poisoning — without warning parents of the potential dangers that their children faced. What’s more, the institute is accused in a still-pending lawsuit of actually helping move low-income families with young children into apartments whose lead was only partly removed so that researchers could determine the effects. Markowitz and Rosner have examined the history of environment-related diseases since the 1980s. In the 1990s, at the request of New York City Law Department, they began looking into the practices of the paint industry and what its leaders knew about lead poisoning risks. They were interviewed by FairWarning’s Lilly Fowler. The interview has been edited for clarity and length.

Lilly Fowler: What is the chief way people are exposed to lead?

Gerald Markowitz: There is some lead in water and in children’s jewelry, but the primary way that children are still being exposed is from the lead in their homes coming from the paint on the walls.

Fowler: Who is at risk for lead poisoning? Is it mainly minorities?

David Rosner: It’s everyone, but especially children, living in a home built before 1978. Every time a house is renovated, every time a nail is driven into a wall, there’s going to be dust that comes out of that wall that will ultimately have lead in it. But it’s worst in older houses that are really in disrepair because of absentee landlords. You can’t just explain it as a problem of poor children. They are the ones who don’t get diagnosed as quickly, and where lead is most prevalent, but every child who lives in an older house is at risk.

Fowler: What are the symptoms of lead poisoning?

Rosner: In the 1930s and ‘40s, the symptoms of lead poisoning were children going into convulsions, going into comas and dying, terrible, terrible deaths. By the time the 1980s came around, the issue of kids dying had largely been resolved and people were patting themselves on the back that we had solved the lead poisoning issue, but researchers had been uncovering the fact that even at lower and lower levels of lead exposure, there were terrible impacts on the neurological functioning of children. Loss of IQ, mental retardation, behavioral disorders, attention deficit disorders, failures at school, behavioral problems, including those that led to delinquency and incarceration.

Markowitz: The amount of lead that doctors and public health officials considered to be harmful to children has gone down dramatically in the last 50 years. In the 1960s, it was generally considered to be 60 micrograms of lead per deciliter of blood. Just last year, it was reduced to 5 micrograms of lead per deciliter of blood. That means, the CDC [U.S. Centers for Disease Control and Prevention] is now saying, that 535,000 children are at risk of permanent damage from lead.

Rosner: They really suspect that there’s virtually no level where we cannot expect neurological damage.

Markowitz: Even the CDC’s figure — I mean to have 535,000 children between the ages of 6 months and 6 years at risk — is a public health disaster. And that is something that is unconscionable in our society. We know how to prevent those injuries and that is to eliminate lead from children’s home environment.

Fowler: How many people are diagnosed with lead poisoning each year?

Markowitz: The number actually diagnosed is much less than the CDC figure because many doctors don’t recognize symptoms. It’s very difficult to know if an individual child’s ADHD is the result of lead poisoning or something else.

Rosner: So you never know whether a child’s IQ would have been five or 10 points higher than it is. There are so many factors affecting intelligence that to ascribe a problem to lead can be very difficult. Kids are seen as particularly at risk because the developing brain is much more susceptible to these impacts. Adults can be damaged, too. The first cases of lead poisoning were identified in workers exposed to lead on the job. In the 1980s, it was a major issue with women working at battery plants and car manufacturing establishments. And it’s still a problem. Lead use has actually increased over the past 30 or 40 years.

Fowler: Which is the main federal agency trying to tackle this issue?

Markowitz: The CDC is trying to look at it in terms of the broadest public health perspective. But the EPA [Environmental Protection Agency] has been very involved in trying to get smelters, for example, to lower their emissions of lead into the atmosphere. OSHA [Occupational Safety and Health Administration] has been very involved about the exposure of workers to lead. HUD [Department of Housing and Urban Development] has been extremely active in trying to reduce the amount of lead that is in public housing. In some ways it’s good that so many agencies are dealing with the problem, but it has inhibited action in some ways because there hasn’t been one central agency that has really made this its major commitment. And so there’s a lack of focus on the national government level.

Rosner: Most agencies I think are pretty scared of this issue. I think it’s fair to say everybody would like to make it everybody else’s issue because the implications of actually trying to prevent lead exposures to children are so vast. So you see at different moments blame being shifted to different agencies because of the fear of the implications of taking on an issue that affects literally millions of homes in the nation.

Markowitz: It costs money to remediate the lead — and in a time where there is a tremendous effort by the Tea Party and others to say that government is not the solution, government is the problem — getting the political will to appropriate the money to protect the health of young children is very difficult to achieve.

Rosner: And, just recently, the CDC basically terminated its lead-screening programs. So they don’t want to look, they’re not even looking, because of, quote, financial reasons. In some sense you could look at the last 40 years as a period of enormous success. Average blood lead levels in children have declined dramatically. I think the average American child now has 1.7 micrograms per deciliter of blood. On the other hand, you still have 535,000 children above 5 micrograms.

Fowler: What about landlords? What agency would be in charge of compelling landlords to ensure that the apartments and houses they rent are lead-free?

Markowitz: There may be individual landlords trying to do the right thing, but for the most part, in the history of lead poisoning, landlords usually have done the minimum that is necessary. It’s only been when they are forced to make changes that they remediate their housing. Public health is very decentralized. In some cases big cities like New York have passed legislation saying you cannot sell a house or you cannot sell an apartment without guaranteeing that it’s lead-safe. But that is on a city-by-city basis.

Fowler: To be exposed, all it takes is being around the paint and breathing in some dust?

Markowitz: For example, if a window has lead paint on it, raising and lowering that window and the friction of raising and lowering that window releases enough dust to potentially damage a child, that little amount of dust.

Fowler: In your book, you talk about researchers who in the 1990s in Baltimore helped place families with young children into apartments they knew had lead, and then measured the children’s blood levels over the course of years to gauge the health effects. How could that kind of research have been considered ethical?

Rosner: They needed to find a new answer to how to address the problem [of lead in homes]. But to really protect kids would mean taking all the lead off walls, which was seen in the Reagan period [when the study was conceived] as a virtual impossibility. So you had this terrible situation where you had no money, no political will and these researchers were finding a way of reducing lead exposure to some, quote, acceptable level without really disrupting landlords. So the origins of the study were in this kind of strange moment of time in which public health was trying to do what it thought was its best. On the other hand, they were giving up on the idea that they could actually prevent disease.

Markowitz: Before the Baltimore study, children were used as canaries in the mine, simply waiting to find out who was lead poisoned, and then fixing the homes. They ended up doing this research project to show that there could be improvement in children’s blood levels by reducing the amount of dust in their homes. But they already knew that the only way to really ensure that a child would not suffer any kinds of deficits was to completely remove the lead from a child’s environment.

Fowler: Why hasn’t the U.S. been more proactive in preventing people from being exposed?

Rosner: It’s important for us to realize that this is like a lot of public health issues. It’s not just lead, but there are a lot of questions about environmental pollutants, about issues of low-level exposures to all sorts of chemicals, that are virtually the same kind of story. We know it’s not good to put endocrine disruptors into our water supply, or to drink out of plastic bottles with BPA or with vinyl chloride, but we do it in kind of a huge, grand human experiment in which we wait for the symptoms of this problem to arise and then we try to deal with it. The problem is that in many ways we continue not to take precautions. We don’t try to protect the population by preventing the introduction of these toxins. What we often do is we wait for the damage to appear and that’s a terrible public health principle. It’s kind of antithetical to everything else in public health, which is a profession focused on  preventing disease. Once the genie is out of the bottle, it’s impossible to put it back, so we are stuck with this predicament.

Fowler: Your book also emphasizes that the paint industry has long known about the dangers of lead. How much of the blame does the industry deserve?

Markowitz: The industry profited by putting lead on walls all across the country. There was a lawsuit that the attorney general of Rhode Island initiated against the lead pigment manufacturers. Both David and I participated in that lawsuit as expert witnesses. The jury came back with a verdict, and said that since these were the companies that put the lead on the walls of the houses of Rhode Island and since they knew that lead was killing children, they should pay for this. It was an incredible verdict.

Rosner: The jury came back and ordered from $2 billion to $4 billion to be paid to the state to remove lead and replace windows in Rhode Island.

Markowitz: Then the Rhode Island Supreme Court reversed that verdict. To this day, the lead industry has been the only group in society that has not paid anything to deal with this problem. Children, of course, pay with their lives. Parents pay with all variety of pain and anguish. The federal government and cities and states pay with special education courses that they’ve got to develop, and there are Medicaid bills that they have to pay. Insurance companies pay, landlords pay to remediate. But the lead industry doesn’t pay and still refuses to pay.

Fowler: Given that lead poisoning is still a problem, what’s the best path forward?

Rosner: It’s to educate the public about this.

Markowitz: If people are aware of how serious exposure to lead is for children, and how many children are affected by lead, they will demand that the money be appropriated by Congress to completely get rid of lead in homes. We’ve known since the 1980s that only complete abatement will really protect a child.

FairWarning (www.fairwarning.org) is a nonprofit investigative news organization based in Los Angeles that focuses on public health and safety issues.